Motor controller



March 20, 1945. J. M. NAUL 2,371,772

MOTOR CONTROLLER Filed DEC. 8, 1942 ww4$= James m. Haul.

Patented Mar. 20, 1945 UNITED STATES PATENT- OFFICE MOTOR CONTROLLER James M. Naul, Fanwood, N. 1., assig'nor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation or New Jersey Application December 8, 1942, Serial No. 468,248

10 Claims. (01. 201-51) This invention relates to manually operable controllers for electric sewing machines, and has for one of its objects the provision of a simplified and improved controller of the carbon disk com.- pression type which has a gradual variation in resistance over a wide range of movement of the manually controlled actuator.

Another object of this invention is to provide a carbon compression rheostat of the pile-type, in which the carbon disks are compressed by means of a-fiat spring, the efiective length of which is decreased proportionally to the pressure applied to the carbon pile.

Another object of the invention is to provide improved means for closing the electric circuit through the carbon pile, and short circuiting the carbon pile when the actuator has reached the point at which the maximum pressure has been applied to the pile. With the above and other objects in view as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawing of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the drawing:

Fig. 1 is a longitudinal vertical section through the controller casing, showing the controller operating mechanism, and the base of the controller in elevation.

Fig. 2 is a top plan view of the base of the controller with the controller unit and its operat-' ing mechanism mounted thereon.

Fig. 3 is a side elevation, showing the side p posite that shown in Fig. 1.

In the embodiment selected for illustration, my improved controller is housed in a casing comprising a hollow top or cover member Ill and a base plate member I I, each of which is preferably molded from synthetic resin, such as Bakelite. Secured on the top-face of the base II by means of the U-shaped sheet metal strap I2 and screws 13 extending through the base plate H, is a carbon compression rheostat comprising a tubular porcelain body 14 housing a stack 15 of carbon disks.

Pivotally secured by the pivot bolt 16 to a lip l1 struck up from the metal strap I2 is a bellcrank lever I8 having one of its ends 19 bent in the form of a U. Between the limbs of the U there is secured by the pin 20 a contact roller 2|.

To the other limb of the lever l8 there is pivotally secured at 22 one end of a link 23, the other end of which is pivotally connected at 24, to a three arm lever 25, fulcrumed at 26, on the ears 21, of a plate 28, fixed to the base ll.

The cover It! is formed with a rectangular opening or guideway 29, in which is fitted a manually operable push button or pedal 30, bifurcated at its lower end to receive the ends of a cross-bar 3| carried by the operating arm of the lever 25. The above described pedal and pivotally arranged lever 25 are old and well known and are more fully disclosed in the patent to Schenk, No. 2,117,257, dated May 10, 1938.

Afiat spring 34 has one of its ends secured to one limb of an L-shaped member 33 fixed to the base II by the screws 33'. The central portion of the spring engages the conducting pressure head 35 of the rheostat and the other end of the spring 34 is formed with an offset portion 36 which rests against the upstanding limb of an L-shaped stop 31, fixed to the base H by a screw 38. It will be understood that the stop 3'! is arranged so that the spring 34 contacts or bears very lightly on the conducting pressure head 35 except when engaged by the roller 2|.

To maintain the bell-crank lever [B in the position shown in full lines in Fig. 2 a sheet metal L-shaped member 40 is fixed to the base II by the screws 4|, and hooked to the upstanding limb of the member 40 in one end of a tension spring 42. The other end of the spring 42 is hooked in a slot 43 in a tongue 44 formed on the lever IS. The spring thus holds the lever IS in its normal or off position, this position being fixed by a shoulder 25 on the lever 25 which shoulder engages the plate 28 as illustrated in Fig. 3, when the lever l8 reaches or position.

Fixed to the base II by the screw 45 is a plate 46 having an upstanding lip 41 formed with a laterally extending portion 48 the purpose of which will be hereinafter explained. For the purpose of adjusting the initial pressure on the carbon pile a screwC is threaded into the base of the tubular body l4 and passes through the base into engagement with the bottom of the carbon pile. By this. arrangement the screw 0 may be adjusted to control the initial pressure of the spring 34 on the carbon pile. A look nut 50 is provided for the purpose of locking the screw in its adiustedposition. The position of the tubular body I! may also be adjusted by loosening the screws, l3, and sliding the body H to the desired position.

Operation When the push button or pedal 30 is pressed downwardly the three-arm lever 25 is swung about its pivot 26. The movement of the lever 25, through the link 23, is communicated to the lever l8 thereby causing the lever l8 to swing about its pivot l6. It will be noted in Fig. 2 that when} the leveris the position shown in full lines, the contact roller 2! does not engage the spring 34. The initial movement of the lever I8 causes the roller 2| to engage the spring 342 and the circuit is thereby closed through the carbon pile resistor.

The circuit at this time: is; as follows: from. the lead A to the plate 46, from the plate through the lead B to a screw C which extends 1 into the porcelain body I and into. engagement: 1 with the carbon stack therein. Through the carance offered by the carbon disk resistor. When the lever f8 finally reaches the position shown in dotted lines, it engages the'v laterally extending portion 48 of thep-Iate 4'6' and the carbon pile is short, circuit'ed. When this occurs the circuitis as follows; from. the plate #6 to the lever 18, thence, through the spring 42 to the plate 40 and the other; side of the line.

I From the above it will be observed that when the spring is first engaged by the roller 2t, circuit through the carbon pileis? established and at this time the effective length or the spring: is at its maximum, thus a very-light pressure is exerted on' the carbon pile, and therefore; the resistance onered' by the carbon disk pile is at its maximum. Further movement of the roller along thes ring decreases the effective lengthor the spring and the pressure on the carbon pile gradually increases until finally the roller is directly over the pressure head- 35 at which time the spring is no longerelfective and the pressure on the carbon tile is at its maximum and the resistance or: rered by the pile is at its minimum.

From the foregoing description considered in connectionwith the accompanying drawings, the construction, manner of operation and several advantages or my improved carbon disk controller will be clearly and fully understood; It is ap parent that such a controller has a wide variety or uses and it will be understood that the form, construction and arrangement of the elements employed are susce tible of materrar variation. Therefore, the privilege is reserved of resorting to all such legitimate changes therein as may be fairly embodied within the spirit of theaccompanying claims.

Having thus set forth the nature of the invention', what I claim herein is F 1 A controller for electric motors comprising a base; a. carbon pile resistor carried by said base;

a flat-spring having one of its ends" fixed to said baseand adapted toexert a pressure on said carbon pile resistor and a pivoted arm having means thereon for engaging the free end or; the spring for the purpose of piacinga tension there;

on, and manual means for swinging said arm about its pivot to increase or decrease the pressure applied to the carbon pile.

2. A controller for electric motors, com-prising a base, a carbon pile resistor carried thereby, a

flat spring adapted to contact one end of the carbon pile resistor, means for securing said spring to; said base, and a manually controlled ivoted arm adapted to engage and travel along.-

said.spring toward the point of contact between the spring and the resistor for the purpose of varying the pressure applied to the carbon pile resistor.

I 3. Acarbon disk controller, comprising a car-' I bondisk resistor, a fiat spring arranged to engage: said resistor between its ends, said sprin having one of its ends fixed, and a pivotally mounted lever for flexing the other end of the spring, said lever having one end movable alongsaid spring to its point of contact with the resistor.

4-. A carbon disk controller, comprising com bination, a carbon disk resistor, a flatcontact spring arranged at one or the resistor to apply pressure thereto, said spring having: one of its ends fixed relative to saidr'esistor, a rnan'ii'a'llt, controlled pivoted lever,- and means carried by said lever for flexing said spring when the lever is swungaboutits pivot tovary the pressure of the spring on said resistor.

5. A carbon disk" controller; comprising in com bin'ation, a carhon disk resistor, a fiat contact spring arranged at one end of the resistor to appiy pressurethereto, said spring havingone of its ends fixed relative to said resistor, a lever carryin an element at one or its ends for em gagein'ent' with said spring, said lever being mounted on a pivot so"- that the end carrying the engaging element moves towards and away from said resistor-and manually controliednreans for actuating said lever.

6. A carbon disk controller,- coniprising iricom bination, a base, a carbon. pile resistor secured to said base, a fiat spring having one of its ends fixed to said base-,- said spring being arranged to engage and apply pressure to the resistor at a point intermediate: the: ends of the spring, a: bellcrank lever pivotally secured at the .iur'rctiort oflits arms to said base, a member carried by one; of the arms of the lever for engagement. with the other end of the spring, spring means tending to maintain said. lever out of contact with. thespring fixed to said base, said spring. being arranged to engage and apply pressure to the resistor at a point intermediate the ends of the spring, a lever pivotally secured to said.- base for movement about a pivot arranged at right angles to the length of the spring, a contact, member carried on one end of said lever and adapted to engage said flat spring and move along the lengthof said spring to the point of enga ement or the spring, and the resistor for the purpose of flexingsaid'spring and thereby vary" the pressure on the carbon pile resistor and l manual means for controlling the position of said lever.

8 A carbon disk controller, comprisingin connbination, a base, a carbon"- pile resistor secured to said base, a flat spring having one of its ends fixed to said base, said spring being arranged to engage and apply pressure to the resistor at a point intermediate the ends of the spring, a lever pivotally secured to said base for movement about a pivot arranged at right angles to the length of the spring, a contact member carried on one end of said lever and adapted to engage said flat spring and move along the length of said spring to the point of engagement of the spring and the resistor for the purpose of flexing said spring and thereby vary the pressure on the carbon pile resistor, means for moving said lever to cause it to engage said spring and connect said resistor in circuit and means effective when said lever reaches a predetermined position for removing the resistor from the circuit.

9. A rheostatic controller comprising, in combination, a base, a tubular shaped carbon disk resistor. secured to said base, a lever pivoted at a point intermediate the ends of said resistor, a fiat spring contacting one end of the resistor and adapted to apply pressure to the resistor upon being flexed and thereby obtain a variation in resistance offered to the flow of an electric current therethrough, a contact element carried by said lever and adapted to contact and flex said spring, spring means tending to maintain said element out of contact with the spring and manually controlled means for moving said lever about its pivot the initial movement of which causes the element to engage the spring and a circuit to be established through said spring and resistor.

10. A rheostatic controller comprising, in combination, a base, a tubular shaped carbon disk resistor secured to said base, a lever pivoted at a point intermediate the ends of said resistor, a flat spring contacting one end of the resistor and adapted to apply pressure to the resistor upon being flexed and thereby obtain a variation in resistance ofiered to the flow of an electric current therethrough, a contact element carried by said lever and adapted to contact and flex said spring, spring means tending to maintain said element out of contact with the spring, a second lever pivoted to said base for movement about a pivot arranged at right angles to the pivot of the first mentioned lever, a link connecting said levers, and a manually controlled sliding member for actuating said last mentioned lever.

JAMES M. NAUL. 

